This method measures the leakage of DNA and lactate dehydrogenase (LDH, EC. 1.1.1 27) from lymphocytes into the surrounding medium as an indicator of cytotoxicity. This method also includes an assay of intracellular (mitochondrial) diaphorase as a measure of cellular activity (MTT assay).﻿

This simple cell culture-based cytotoxicity test (in which cell viability is determined by uptake of the dyes ethidium bromide and fluorescein acetate) has been developed as a general test for acute toxicity.

Tumour cell lines cultured as aggregates can be utilised for in vitro radiosensitivity and/or chemosensitivity tests. Chemical effects are monitored by studying the changes in spheroid diameter measured by laser diffraction.

This protocol provides a generic description of a simple assay, which can be used to determine the viability/number of cells in culture. The qunatitative measurement is made through a formation of a coloured product (in a mitochondria-dependent reaction) to which the cell membrane is impermeable.

The activating system (human liver microsomes) is separated by a semi-permeable membrane from the target cells (human mononuclear leucocytes or red cells) in order to identify cytotoxic metabolites that are capable of diffusing away from the site of production.

The absorption of UV at 260nm in a fixed volume of solubilised cells is proportional to the cell number, and therefore can be used as a simple means of obtaining a cell count. Cell counts obtained in this way can be combined with measurements of the inhibition of DNA synthesis ([3H]-thymidine incorporation) by test compounds, to produce an index of cytotoxicity.